Pain physician
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Paresthesia-based spinal cord stimulation (SCS) depends upon dorsal column (DC) fiber activation to engage pain-relieving neural mechanisms. However, the mechanisms for 10-kHz paresthesia-free SCS have not been fully elucidated. Preclinical work has shown selective drive of inhibitory dorsal horn neurons, while other hypotheses suggest that DC fibers may be activated. To provide clinical data for guiding mechanism work, we analyzed paresthesia perception thresholds (PPT) over a range of low to high kHz frequency and compared those values to the stimulation parameters from the therapeutic 10-kHz SCS programs used by patients. ⋯ Therapeutic 10-kHz SCS uses stimulation amplitudes far lower than the PPT, providing evidence that therapeutic 10-kHz SCS does not activate dorsal column axons. Additionally, the PPT decreases with increasing kHz frequency, suggesting that a presumed asynchronous pattern of activation from kHz stimulation does not raise the threshold at which sensation occurs.
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Opioids, which are widely used during surgery in perioperative settings, may cause hyperalgesia, especially when the opioid employed is remifentanil. Opioid-induced hyperalgesia may increase the length of a patient's hospital stay and negatively affect enhanced recovery after surgery and the patient's prognosis. Currently, there is no consensus on treatment strategies for remifentanil-induced postoperative hyperalgesia (RIPH). ⋯ Our results demonstrated that the upregulation of LCN2 in the ACC plays a crucial role in the occurrence of RIPH, suggesting that LCN2 potentially be a therapeutic target for alleviating RIPH.